1. Field of the Invention
The present invention relates to an ink jet cartridge which is charged with ink and is set in an ink jet printer to discharge drops of ink at a medium of record such as a recording paper, and, in particular, to a thin type ink jet cartridge in which the structure is reinforced and the ink is effectively utilized.
2. Description of the Related Art
Recently, ink jet printers have been utilized to record information on recording paper because such printer can operate at a low noise and at a high speed. In addition, because of downsizing of desk top type of computers to lap top type or notebook size type of computers to a small size is required. An ink jet cartridge put in the ink jet printer has been rapidly utilized because the cartridge can be easily exchanged for another and a small-sized ink jet cartridge can be easily provided at a low price.
2.1. Previously Proposed Art
A conventional ink jet cartridge is described with reference to FIGS. 1 to 4.
FIG. 1 is a disassembled diagonal view of a conventional ink jet cartridge.
As shown in FIG. 1, a conventional ink jet cartridge 11 is provided with a box type of ink packing portion 12 formed by a porous material in which ink 13 is packed, a box type of body 14 in which the ink packing portion 12 is accommodated, an ink cover 15 for holding the ink packing portion 12 in the body 14, and an ink discharging head 16 through which the ink 13 is discharged from the ink packing portion 12 to a recording paper.
The ink packing portion 12 is provided with an ink filter 17 for filtering dirt and bubbles in the ink 13 when the ink 13 is supplied to the ink discharging head 16 according to the capillary phenomenon.
The body 14 is provided with an ink supplying hole 18 through which the ink 13 packed in the ink packing portion 12 is supplied to the ink discharging head 16.
The ink discharging head 16 is provided with ink discharging nozzles 19 for discharging the ink 13 supplied from the ink packing portion 12 and an electric energy control portion 20 for controlling the discharge of the ink 13 by applying electric energy to respective heaters (not shown) which boil the ink 13 supplied to the corresponding nozzles 19. That is, the ink 13 boiled in the nozzles 19 is discharged to a recording paper because the ink 13 is rapidly expanded. In this case, because the size of the nozzles 19 is small, a drop of ink is discharged from each of the nozzles 19.
FIG. 2A is a plan view showing a drop of ink discharged at a recording paper from the cartridge shown in FIG. 1, and FIG. 2B is a side sectional view showing a drop of ink discharged at a recording paper from the cartridge shown in FIG. 1.
As shown in FIGS. 2A and 2B, drops of ink 21 are discharged from the conventional ink jet cartridge 11 at a line of a recording paper 22. The recording paper 22 is sent out by a column-shaped platen 23 to receive the drops of ink 21 at a following line of the recording paper 22. In addition, the recording paper 22 is held on the platen 23 by a holding plate 24 to correctly send out the recording paper 22. The conventional ink jet cartridge 11 is put in an ink jet printer (not shown) and is received to be movable in an axis direction along the platen 23 to print out letters on lines of the recording paper 22.
In the above configuration of the conventional ink jet cartridge 11, the ink 13 packed in the ink packing portion 12 is supplied to the ink discharging head 16 through the ink supplying hole 18 according to the capillary phenomenon. Therefore, the ink 13 is filled up in all of the ink discharging nozzles 19 of the ink discharging head 16. In this case, dirt and bubbles contained in the ink 13 are filtered off when the ink 13 passes through the ink filter 17.
Thereafter, when a discharging signal is transmitted to the electric energy control portion 20 to print out a prescribed letter on the recording paper 22, electric energy is applied to heaters corresponding to the nozzles 19 selected by the discharging signal. Therefore, the ink 13 supplied to the selected nozzles 19 is boiled because the ink 13 is heated by the energized heaters. That is, a portion of ink 13 in the selected nozzles 19 is vaporized so that the pressure of the ink 13 in the selected nozzles 19 is rapidly increased.
As a result, drops of ink 21 are discharged from the selected nozzles 19 to print out a letter on a line of the recording paper 22. In this case, the print of a series of letters on a line is accomplished when the ink jet cartridge 11 is moved from one end of the printer to the other end in an axis direction of the platen 23. Thereafter, the recording paper 22 is sent out by the platen 23 so that letters are printed out on a following line of the recording paper 22 in the same manner.
Accordingly, the recording paper 22 can be printed out by the drops of ink 21 discharged from the conventional ink jet cartridge 11.
2.2 Problems to be Solved by the Invention
However, in cases where the conventional ink jet cartridge 11 is thinned to miniaturize the ink jet printer, the stiffness of the body 14 deteriorates. Also, in cases where the wall thickness of the body 14 is thinned to manufacture a thin type ink jet cartridge to miniaturize the printer, the stiffness of the cartridge deteriorates in the same manner. Therefore, when the conventional ink jet cartridge 11 is put in the printer, the body 14 is elastically pressed by operator's fingers and/or the printer so that the body 14 is distorted and the porous material forming the ink packing portion 12 is pressed. As a result, the ink 13 is forcibly pressed out. That is, the leakage of the ink 13 is generated.
Also, because the ink 13 is injected in the porous material, the ink 13 permeates the porous material. Therefore, some ink 13 necessarily remains in the porous material even though the cartridge 11 is used up and no more ink 13 is not supplied to the nozzles 19. In addition, in cases where the cartridge 11 is miniaturized, the ratio of the remaining ink 13 to the packed ink 13 is increased. Therefore, the effective volume of the ink 13 is decreased. Accordingly, the cartridge 11 cannot be used for a long time and 11 must be often exchanged for another.
Also, the volume of the remaining ink 13 in the conventional ink jet cartridge 11 cannot be checked because the ink packing portion 12 is sealed by the body 14 and the cover 15. In addition, even though the body 14 is made of transparent material to make the ink packing portion 12 visible, the volume of the remaining ink 13 cannot be checked because the ink 13 permeates the porous material. That is, even though a comparatively large volume of ink 13 is consumed, it is difficult to distinguish the color change of the surface of the porous material.
Also, in cases where a user exchanges a used cartridge 11 for a new one because the ink 13 in the used cartridge 11 is consumed, the user often touches the nozzles 19 because the nozzles 19 are exposed. Therefore, the user stains his fingers with the ink 13, and dust sticks to the nozzles 19 so that the nozzles 19 are sealed. In addition, when the new cartridge 11 is attached to an ink jet printer, the cartridge 11 is sometimes hit against the printer so that the nozzles 19 are damaged. Therefore, drops of ink 21 cannot be discharged from the new cartridge 11.
Also, as shown in FIG. 3, in cases where a perforated continuous paper 25 is utilized as the recording paper 22, a perforated portion 26 of the paper 25 touches the nozzles 19 of the cartridge 11 so that the paper 25 is stained.
Finally, as shown in FIG. 4, in cases where the recording paper 22 is curved or bent to float above the platen 23 because the recording paper 22 is not smoothly sent out by the platen 23, a curved portion of the paper 25 touches the nozzles 19 of the cartridge 11 so that the paper 25 is stained with the ink 13.